Oral Defenses and Disease: Salivary Gland Function 1

Recent studies on parotid gland flow rate and composition in healthy subjects do not support the conventional wisdom that there is a gradual deterioration in salivary gland function with aging. With gustatory stimulation a diminution in flow rate was observed only in post-menopausal women taking medications. Studies of whole saliva and preliminary studies of submandibular saliva flow rate, however, suggest that these glands may exhibit functional changes not seen in the parotid. This would be consistent with histological findings. Reports to date on age effects on composition suggest modest selective changes in electrolytes (e.g. sodium) and only subtle changes in proteins (e.g. amylase isoenzymes). Clinical concerns (rampant caries, stomatitis, periodontal disease) arise largely because of the high number of elderly on medications or therapeutic interventions that affect salivary flow and the increase in incidence of diseases of the salivary gland (e.g. sialadeneitis, Sjogren's, sarcoidosis). Reduction in flow rate and alterations in composition diminish salivary protective mechanisms, i.e. antibacterial activity, lubrication and protection of soft tissues, and maintenance of hard tissue integrity. Recent research on structure of mucins, the nature of the salivary lipids and interactions among salivary proteins should stimulate a second generation of studies on both the effects of aging per se and aberrations resulting from disease. Stimulation of compromised function and development of more effective salivary substitutes are also important areas of research.